of serine iaydroxymethylaseY and glycine, hFH4 is converted to FHd (equation 2) Glycine + hFH4 J _ Seriiie + FHa (2) Treatment of hFH4 with hFf& dehydrogenase9 and T P N produces equivalent amounts of ''actixTc formyl" and T P N H according to equation 3
of both ferrocene and benzene aromatic rings have now been observed in the case of several ferrocenyl and phenyl alcohols through iiii'rared absorption studies using ;t Perkin-Elmer Model 2 1 spectronxter with LiF optics. For example, the spectrum of a-hydroxyethylferrocene in CCI4 exhibits both the free hydroxyl absorption band at 3617 cln. and another concentration-independelit, but tellihFII, + T P N + Z f F H , + TPNH + I-I+ (3) perature-dependent, hydroxyl absorptioii hand of The results of two typical experiments may be greater intensity a t 3574 c m - l corresponding to summarized as follows: (a) 0.070 pnole of ~ F H J that fraction of the niolecules a t equilibrium having produced O.OGG pmole of TPSH; and (b) 0.024 a ring-hydrogen bonded structure of the probable pmole of hFH4 was converted to 0.0% pnmle oi representation I . Similarly, /3-phenylethanol exfPH4 (measured as f5-l0 FH4). hibits the sanie corresponding absorptions a t 3630 hFH4 is decomposed by treatment with hydroxyl- and 3601 respectively, but with reversed aniine or acetylacetonelO; the latter reagent can in t en4 t ies . he used to estimate the bound HCHO in hFH?. The stability constant (Kdiss2 for reaction 1 iii reverse) of hFH4, and the resistance of the conipound I to air-oxidation, suggests that hFH4 is the NbI,?jlahydroxymethylll bridge compound (hb--'OFH4) \ rather than h5FH4 or h10FH4. This conclusion has been reached also by other i n ~ e s t i g a t o r s , ~ and J is consistent with our previous finding,12 t h a t with purified preparations of hFH4 dehydrogenase, f5-10FH4,rather than f5FH4 or f10FH4,is the reaction product in equation 3. I !I (9) I-.Hateti, 11. J. Osborn, I,. D . K a y a n d F. 11. Hueiinrkeris, The homoannular-diacetylferrocene first prepared .I. Bioi. CLpm , 2 2 7 , 637 (1957). by Rosenblum and Woodward5 arid presumed to (10) T. iiash, Biochem. J . , 65, 41G (1953). (11) Bec:tuse t h e t e r m "active hydroxymethyl" is alrt,ady estab. have the 1,3-structure was shown here to have the li>hrd in t h e litrrntrire, i t is retained here [wen thuur:h t h e structure 1,2-structure6on the basis of a n intramolecular hyl i j - IfiFH, represctits a methyleiic, r it!irr tl::it! a hydrnuymetbyl. drogen bond between the two hydroxyl €unctions of the corresponding diol, 1,2-di-a-hydroxyetliyI; t i press ferrocene. I n the present connection, however, the 11:) Rescarch I'rllow of t h e N:itionul Ins!itute o f hrthriti- atid point of interest is t h a t in addition to the intra-hy Iletabolic Diseases, Tublic IIenltli Service droxyl halid a t 3457 cm.--l, the only stretching frc( 1 4 1 Po.~t-doct~,ral Fellwv or t h e ii.ntiiirinl lIltli S c r r l c e . yuency of the second hydroxyl group observed is a t 3555 an.-', i.e.? in the ring-hydrogen bonded state hr. J. o S B O R ? i ' 3 E. N. VERCAMER (11). Similar free hydroxyl approach for interacP. T. TALBFRT" tion with the aromatic ring is permitted here as in I, while in the contrasting parallel case of the intramolecularly hydrogen bonded 1,l'-di- a-hydroxyethylferrocene, the structure does not permit close approach of the free hydroxyl to either of the two INTRAMOLECULAR AROMATIC RING--HYDROGEN BONDING' aromatic rings resulting in a characteristic free band a t 3G21 cm.-'.' Sir: The hydrogen bonding role of the ferrocene ring Evidence has been available indicating the occur- also was demonstrated intermolecularly in CC14 rence of intermolecular hydrogen bonding between with a solution 0.1 M in both ferrocene and n-huts-alcohol solutes and benzene aromatic solvents no1 through the appearance of a new, additional through observation in the overtone2 and funda- weak hydroxyl absorption a t 3597 tin.-'. mental3 spectral region of the greater shift of the 1T:ith the magnitude of Av as a measure of the hydroxyl stretching frequency in these solvents strength of a hydrogen b ~ n d ,it~ is . ~clear froni the with respect to the vapor state than in cc14 solvent. Av value for a-hydroxyethylferrocene (43 cm. - I ) However, there has not yet been reported any in- compared to the \-due for ,&-phenylethanol (?!I stance of the important general case of an intramolecular structure involving hydrogen bonding to cm.-l) that the n-electron system of the ferrocene (4) H. K w art. private co;nmunication, also tias informed LIS of h i :in aromatic ring. Such an instance would additionally provide a clarifying distinction between observatiun r,f these t w o hands. ( 5 ) M. Roseublum, P h . D . Thesis. Harvard Uuiversity, 1053. the previously combined roles of the aromatic sys(6) J. H Richards and 'r 1 Curphey, Ciien?i.rtry otzd I j ? h 1 s L r ? , tem as both solvent and reactant. 14.56 ( I O R C , ) , h a v e independently nnrlc this s a m e 1,2-structur? Interesting examples of this type of intranio- m e n t u i n anhydride formation f r o m the corresprmdinp diacid. ( 7 ) Other additionally interesting aspects of t b r ,pectra :issuci&tril lecular hydrogen bonding to the n-electron systems I ,
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1 ' ?'his w r k was supported in p a r t by the Army a n d X a v y under
Siqnai Corps Contract S o . DA-036-39SC-70151. (21 I. 11. Jones a n d R . M. Badger, THISJ O C R X A I . , 73,3132 (1!151) ( R \T 'r:iInre-, ihld , 74, 337.7 (195?r
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with the h y d r o x y l groiir)s of these diol.; ioqvtI>crw t h zi 1nore detailed and rjuantitativr awmint 91 t h e i t .
